Carbon dioxide (CO2) is a greenhouse gas that, as a byproduct of combustion and a wide variety of industrial processes, is subject to increasing regulation. As a result, there is a significant interest in efficient methods for capture CO2 from such gas mixtures. Such methods are often designed to capture CO2, at low pressure (for example, from flue gas), and typically are energy intensive. In traditional processes, an aqueous chemical solvent (typically an aqueous solution of MEA. AMP, and/or piperazine) is utilized in an absorber to absorb CO2 in the form of chemical complexes with the solvent species and water, generating a rich solvent. A stripper is utilized to release CO2 from the rich solvent through the application of heat, to produce a lean solvent. In such processes a cross exchanger is utilized to improve efficiency by exchanging heat from the lean solvent into the rich solvent. The net heat that is added to the process is referred to as the stripper duty or heat rate. This heat rate not only represents a considerable expense, the production of the necessary heat (for example, steam production) can result in the generation of additional CO2 and/or reduction of the output (for example, electricity) of the plant.
Thus, there is still a need for methods and compositions that reduce the costs associated with chemical solvent-based CO2 capture.